Microbiology- tree of life

bacterial cell average size

1 micrometer, but vary a LOT

cell size comparison

eukaryotic > bacterial cells > viruses

all cells have ____?

• cytoplasmic membrane

• cytoplasm

  • ribosomes

  • metabolic enzymes

• DNA

• animals use cytoskeleton for shape (not a wall)

which cells have walls?

bacteria, fungi, plants

eukaryotic cells: what do they have that prokaryotes do not? & DNA info

• membrane-bound organelles

• membrane-bound nucleus

  • DNA within nucleus

    • linear, diploid, mitosis & meiosis, sexual reproduction

prokaryotic cells: DNA info

• condensed within nucleoid region

• single circular chromosome, haploid, no sexual reproduction

what do virus structures lack?

• cytoplasm

• ribosomes

• metabolism

what do virus structures contain?

• nucleic acid genome

  • DNA/RNA , single/double strand

• protein capsid

• sometimes membrane

how do viruses reproduce?

must infect a pro/euk cell in order to reproduce

naked vs enveloped virus

enveloped: has an envelope (membrane) with glycoprotein, and capsid

naked: no membrane, only capsid

types of classification methods

Linnaeus, Haeckel, Whittaker

Linnaeus classification

• two kingdoms

  • animalia: higher animals and protozoa

  • plantae: higher plants, algae and fungi

*no prokaryotes in either kingdom

Haeckel classification

• 3 kingdoms:

  • animalia

  • plantae

  • protista

• believed Darwin’s theories of evolution - Darwin’s #1 fan

• invented “phylogeny” - evolutionary tree of organisms

Whittaker classification

5 kingdoms:

• animalia

• plantae

• protista

• fungi

• monera

Woese & molecular-based approach to phylogeny

• 16s rRNA in prokaryotes

• 18s in eukaryotes

All cells have ribosomes- rRNA essential for translation

• easy to sequence, evolved slowly

molecular-based approach to phylogeny: phylogenic trees

generated by looking at sequence differences in rRNA

• led to 3 domains of life

3 domains of life

• bacteria

• archaea

• eukarya

*LUCA: last universal common ancestor —> diverged into 3 domains

endosymbiosis

• evolution of mitochondria

bacteria were engulfed by ancient eukaryotes

evolved into eukaryotic organelles (mitochondria)

classification: energy use

chemotrophy - use chemicals

phototophy - use light

classification: carbon use

heterotrophs: use organic compounds as carbon source

• sugars, proteins, lipids, amino acids

autotrophs: use CO2 as carbon source

• photosynthesis, chemosynthesis

classification: energy & carbon use

• chemoheterotroph: E & C from organic molecules

• chemolithoautotroph: E from inorganic molecules, C from CO2

• photoautotroph: E from light, C from CO2

• photoheterotroph: E from light, C from organic molecules

bacterial diversity

• highest diversity

• largest 4 groups:

  • Proteobacteria (Gamma, Beta, Alpha, Zeta, Epsilon, Delta - highly diverse within group as well)

  • Bacteroidetes

  • Actinobacteria

  • Firmicutes

archaeal diversity

• mostly- extremophiles

• halophiles

• methanogens

• hyperthermophiles

eukaryal diversity

• mostly- single cell microbes

• fungi, plant, and animals are included

  • all are multicellular

life evolution vs earth’s history

• earth originated 4.6 bya

• bacteria and archaea- 4 billion years ago

• eukaryotes- 2 billion years ago

  • 1st endosymbiosis event: mitochondrial origination - early in eukaryote evolution

  • 2nd endosymbiosis event: chloroplast origination